Can anyone advise on reparing or replacing a low-voltage recessed can that has apparently failed? It's not the bulb, as I've tried replacing that already, the bulbs are fine. It's not the switch (no dimmer), as the other three cans are fine. I suspect it's the magnetic transformer, but I'm not sure how to access it or how to order a compatible part.

The can is one of about 30 4" low-voltage halogen fixtures installed about five years ago during a full remodel. It's a new-construction housing, an Elco EL1499ICA:
http://www.elcolighting.com/products/4-low-voltage-airtight-ic-housing
There is attic access but the specs show the transfomer and can built into a large metal box. Are the transformers generally designed to be accessible through removing the can? I took the trim off, and there are some screw heads in the can - I don' t know if unscrewing those will loosen the can and access the transformer through the ceiling.

I've had no trouble with the lighting/electrical since the remodel, not even had to replace a single MR16 halogen bulb in five years. But the light on this one started flickering a bit a few months ago, and then just died completely last week.